It's simpler than the title suggests.
When I log into a remote application via Citrix XenApp from Box A (Windows XP) and Box B (Windows 7) I can see all local physical disks and locally mapped network drives, in addition to the drives mapped within the remote application itself.
However, when I log into that same application from Box C (a virtual Windows 7 environment) I can't see any local drives at all, whether "physical" or mapped.
Because the drives can be seen from Box A and B I know that the remote environment is mapping the drives OK (i.e. XenApp is set up correctly) but Box C is obviously hiding these drives from the remote application.
How is that being done and is there anyway I can confirm it what restrictions are in place using just regedit. I don't have access to admin tools.